JPH04267110A - Reusing method of waste at time of working of laminate - Google Patents

Abstract

PURPOSE:To reuse waste by cutting waste such as trimming loss generated at a time when a sheet-shaped laminate, in which a base sheet and a skin material are laminated, is thermoformed into splinters, melting and kneading the splinters by a kneading extruder and recovering the melted and kneaded splinters as pellets. CONSTITUTION:When waste generated in a process, in which a sheet-shaped laminate, in which a woven fabric or a nonwoven fabric composed of thermoplastic resin fibers is laminated on a solid type base sheet consisting of a polyolefin thermoplastic resin containing a not less than 50wt.% propylene component and/or ethylene component or a base sheet, in which the foam type base sheet made up of the same resin or/and said solid type base sheet are laminated, as a skin material, is molded, waste is cut into splinters without removing the fibers of the skin material. The raw material resin of the base sheet is added to the splinters or is not added and charged into a kneading extruder and melted and kneaded, and melted and kneaded splinters are recovered as pellets. The pellets are reused for manufacturing the base sheet.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for recycling waste from the processing of laminates, and more specifically, to a sheet-like base material made of a polyolefin resin, a woven fabric or a non-woven fabric made of thermoplastic resin fibers is used. This relates to a method of collecting and recycling waste such as trimming loss generated when thermoforming a sheet-like laminate, which is laminated as a skin material and is suitable for use in automobile interior parts, etc. be.

0002

[Prior Art] A sheet-like laminate is obtained by laminating a resin sheet made of a polyolefin resin as a base sheet and a woven fabric or non-woven fabric made of thermoplastic resin fibers as a skin material. It is well known that thermoforming into the shape of During such processing, waste materials such as trimming loss are generated. Conventionally, when attempting to reuse such waste, the waste was crushed, the resin component of the base sheet and the fiber component of the skin material were separated, the fiber component was discarded, and the resin component was recovered and used. Was.

0003

Problems to be Solved by the Invention The above-mentioned recovery methods have the disadvantage that the fibers are discarded without being reused, and the equipment used for crushing and separation is expensive. The reason why the fibers were separated in this way is that if they were not separated, the fibers would get caught in dies etc. when the resin was mixed into the extruder for reuse, making production unstable.
In addition, the fibers become fuzzy during the crushing process, making it difficult to handle the resin unless the fibers are separated.

0004

[Means for Solving the Problems] The present invention solves the above-mentioned difficulties, and it is possible to solve the above-mentioned problems without separating the fibers of the skin material from the waste, and therefore without requiring a special device for separating the fibers. The purpose of the present invention is to provide a method for recovering waste materials in a state where they can be reused.

The present invention achieves the above object, and its gist is to provide a solid base sheet made of a polyolefin thermoplastic resin containing 50% by weight or more of a propylene component and/or an ethylene component; A woven fabric made of thermoplastic resin fibers is added to a foam base sheet made of a polyolefin thermoplastic resin or a base sheet formed by laminating the solid base sheet and the foam base sheet. Or a method of recycling waste generated in the process of thermoforming a sheet-like laminate made of nonwoven fabrics as a skin material, wherein the waste is recycled without substantially removing the fibers of the skin material from the waste, The strips are cut into thin pieces, and the pieces are fed into a kneading extruder with or without addition of the raw material resin for the base sheet to mix the resin for the base sheet and the fiber resin for the skin material. Knead at a temperature above the melting point until the resin of the fibers and the resin of the base sheet mutually dissolve, or the resin of the fibers is dispersed in the resin of the base sheet in the form of a phase-separated body with a size of 20 μm or less. A laminate characterized in that the pellets are recovered as pellets, and the pellets are used to manufacture the above-mentioned solid-form base sheet, foam-form base sheet, or a base sheet formed by laminating both of these sheets. It consists in a method of recycling waste from body processing.

[0006] Examples of waste materials to be recycled in the present invention include the following. The first is a solid base sheet (usually 0.3 to 5 mm thick) made of a polyolefin thermoplastic resin containing 50% by weight or more of a propylene component and/or an ethylene component, which is made of thermoplastic resin fibers on one side. Woven or nonwoven fabrics are laminated as skin materials to form a laminate. This laminate is thermoformed into the shape of its intended final product. For example, when used as an interior material for an automobile, the material is thermoformed, such as vacuum forming, pressure forming, or vacuum pressure forming, with the skin material facing outside. In these molding processes, trimming loss and the like are inevitably generated as waste. Such waste is the object to be recycled in the present invention.

[0007] As the second waste, the same polyolefin thermoplastic resin sheet foam as above is used as a base sheet (thickness is, for example, 0.5 to 10 mm), and the same woven fabric or Examples include waste such as trimming loss that is generated when nonwoven fabric is laminated as a skin material and the laminated body is thermoformed.

[0008] In the present invention, the base sheet is further formed by laminating the solid base sheet as described above and the base sheet made of sheet-like foam, and a woven fabric or non-woven fabric similar to the above is added to the base sheet. It is also applicable to waste products such as trimming loss generated when the laminate is laminated as a skin material and the laminate is thermoformed. In this case, the base sheet may be one in which a foam base sheet is laminated on one side of the above-mentioned solid base sheet, or a solid base sheet is laminated on both sides of a foam base sheet. Becomes an object.

[0009] To illustrate the thickness of each constituent layer of a sheet having a structure in which both sides of the above-mentioned foam-shaped base sheet are sandwiched between solid-shaped base sheets, the thickness of the foam-shaped sheet constituent layer is 0. .5 to 9.9 mm, and the thickness of the solid sheet constituent layers laminated on both sides is 0.05 to 2.
The sheet thickness of the laminated three-layer structure is preferably in the range of 10 mm or less. Note that such a sheet having a three-layer structure can be manufactured by a lamination method such as a thermal bonding method, extrusion, dry lamination method, or coextrusion method.

The polyolefin thermoplastic resin constituting the above-mentioned solid base sheet, foam base sheet, and base sheet formed by laminating both types of sheets includes ethylene and/or propylene. Copolymer resins containing at least 50% by weight of ethylene and propylene components, such as polyethylene (homopolymers produced by high-pressure, medium-pressure, and low-pressure methods) and polypropylene (homopolymers), as well as copolymer resins containing at least 50% by weight of ethylene and propylene components, such as ethylene. and other α-olefins, vinyl acetate, acrylic acid or acrylic acid esters, or polypropylene resins obtained by random, block or random-block copolymerization of propylene and 1 to 15% by weight of α-olefin. be able to.

[0011] Various additives such as heat stabilizers, ultraviolet absorbers, antioxidants, colorants, etc. can be used in combination with the above-mentioned resin materials, if necessary. The resin preferably has a melt index of 0.5 to 20 g/10 min.

The foamed resin layer of the base sheet forming the laminate of the present invention is made of substantially closed cells. Foaming agents that can be used to form this foam layer can be broadly classified into chemical foaming agents and physical foaming agents based on their foaming mechanism.Chemical foaming agents include azodicarbonamide, dinitropentamethylenetetramine, azodiisobutyrochloride, etc. Examples of physical blowing agents include butane, heptane, hexane, dichlorodifluoromethane,
Examples include nitrogen and carbon dioxide gas.

When foaming the foamed resin layer, small amounts of inorganic powders such as talc and silica, metal oxides such as zinc white (zinc oxide) and litharge (lead oxide), stearic acid, Fatty acids such as lauric acid or metal salts of these fatty acids (eg, salts of zinc, calcium, lead, barium, etc.) can be added.

In the resin foam layer, the blending ratio of the raw resin and the blowing agent is not particularly limited, and varies depending on the type of blowing agent, etc., but the foaming ratio is 1.2 to 5 times, preferably 1.5 to 3 times. It should be set so that This resin foam layer preferably has small cell diameters.

As the skin material forming the laminate of the present invention, woven or nonwoven fabrics of thermoplastic resin fibers such as polyethylene fibers, polypropylene fibers, polyester fibers, polyamide fibers, polystyrene fibers, and polyacrylic fibers are used. In order to laminate these skin materials on a base sheet, the temperature must be within the range below the melting point of the resin constituting the base sheet (melting point -30°C), preferably below the melting point (melting point -30°C).
While the base sheet is held in a temperature range of 20°C or higher, the skin material is stacked and pressurized to a pressure of, for example, 1.5 to 5 kg/cm.
Pass through the rolls under a roll pressure of 2 to laminate. In addition, the skin material and base sheet are made of ethylene vinyl acetate copolymer,
Lamination may be performed using an adhesive made of ethylene-propylene rubber, unsaturated carboxylic acid-modified polyolefin resin, or the like.

The laminate obtained by laminating the base sheet and the skin material as described above has a temperature below the melting point of the resin constituting the base sheet (melting point -30°C), preferably below the melting point. It is thermoformed into a desired shape at a temperature within the range of (melting point -20°C) or higher. Any heating method can be used during thermoforming, such as hot air heating,
Examples include radiant heating methods using infrared heaters, far-infrared heaters, and the like. In addition, thermoforming methods include vacuum forming method,
A pressure forming method, a vacuum pressure forming method, a stamping molding method, etc. are used.

[0017] In the present invention, waste such as trimming loss generated in the process of thermoforming the laminate is directly processed using a cutting machine or the like without substantially separating the fibers of the skin material contained therein. Cut into strips. Here, the strips include at least 50%, preferably at least 70%, of shredded pieces whose maximum dimension is 10 mm or less,
Other parts also refer to those whose longest dimension is 20 mm or less. The pieces are put into a kneading extruder and kneaded at a temperature higher than the melting point of the resin of the base sheet and the thermoplastic resin fiber of the skin material, so that the thermoplastic resin fibers are mixed into the base sheet. or the fibers are phase separated with a size of 20 μm or less (i.e., a portion that is not fully fused and remains with a different phase in the fused resin).
After kneading the mixture until it becomes dispersed in the molten resin of the base sheet, it is extruded into strands from a die and collected as pellets.

[0018] When the above strips are put into a kneading extruder,
A polyolefin thermoplastic resin (unused product) used for manufacturing the base sheet may also be charged into an extruder and kneaded. Thus, the weight ratio of the resin in the base sheet portion of the collected strips fed into the extruder to the unused resin is 100/
It is preferably selected from the range of 0 to 20/80.

The pellets obtained from the kneading extruder as described above are used as a raw material for manufacturing a base sheet for manufacturing the above-mentioned laminate. Pellets obtained by adding unused polyolefin resin to the collected pieces can be used as they are for producing a base sheet. When using pellets obtained only from small pieces of recovered products without adding unused polyolefin resin, unused polyolefin resin may also be supplied to the extruder for sheet production. good. Further, when manufacturing a base sheet made of sheet-like foam, a foaming agent is added.

[0020] In the above manner, a base sheet is obtained by reusing waste such as trimming loss, and this base sheet is made of (a) the resin of the base sheet that constituted the waste;
(b) It consists of the added unused polyolefin resin and (c) the resin of the skin material fibers that constituted the waste. In the above-mentioned sheet, the content of the resin component (c) is preferably 30% by weight or less, preferably within the range of 0.1 to 30% by weight. If the content exceeds 30% by weight, the moldability of the sheet-like laminate produced therefrom will deteriorate, which is undesirable.

[0021]

EXAMPLES Next, examples of the present invention will be described, but the present invention is not limited to these examples unless the gist of the invention is exceeded. Example 1 In this example, polypropylene (MFR of 1.1 g/1
The base sheet is a solid sheet with a thickness of 1.8 mm, which has a density of 0.90 g/cm3 and a melting point of 160°C.
) fibers (thickness is expressed in basis weight, 2
The trimming loss generated during the process of vacuum-pressure forming a sheet-like laminate made of 00g/m2) as a skin material is recycled. This waste is then cut into dice (5 mm x 5 mm) using a cutting machine without separating the skin material.
) into strips (hereinafter, this process will be referred to as cutting process). In this strip, the weight ratio of the amount of resin in the base sheet to the amount of resin in the fibers of the skin material is 90:10.

[0022] In addition to the above strips, polypropylene pellets (unused) used for manufacturing the above base sheet
are mixed in a weight ratio of 50:50. The resin content of the fibers of the skin material in this mixture is 5% by weight. This mixture was supplied to a twin-screw kneading extruder (screw diameter 40 mm) and kneaded at a maximum processing temperature of 270°C to produce pellets with a diameter of 3 mm and a length of 5 mm. Hereinafter, this process will be referred to as kneading and fusing process.

In the obtained pellets, the fiber resin in the skin material part of the waste is in the form of a phase-separated body with a size of 20 μm or less in the fusion of the polypropylene in the base sheet part of the waste and the added unused polypropylene. It was dispersed. In addition, this state can be confirmed by observing the sample with a microscope and
The determination is made by checking whether there are substantially no phase separators of m or more.

[0024] The pellets obtained in the above manner were
Using a single-screw extruder (screw diameter 40 mm) equipped with a 11 mm wide T-die, the processing temperature (extrusion temperature) can be increased to a maximum of 21 mm.
It was extruded into a sheet at a temperature of 0°C and a molding temperature of 170°C (hereinafter, this operation is referred to as sheeting processing). The thickness of the obtained sheet is 1.8 mm. This sheet is used as a base material sheet, laminated with a skin material, and reused.

Example 2 In this example, a sheet foam (2.4 mm thick) made from the same polypropylene as used in Example 1 was used.
The trimming loss generated when vacuum-pressure forming a sheet-like laminate made of the same polyethylene terephthalate fiber nonwoven fabric (thickness: 200 g/m2 in basis weight) used as the skin material used in Example 1 was disposed of as waste. . The sheet-like foam was produced by using a mixture of azodicarbonamide and zinc oxide in equal weight proportions as a blowing agent, and blending this blowing agent in a ratio of 6 parts by weight to 100 parts by weight of polypropylene.

The above waste material is cut to the same size without separating the skin materials in the same manner as in the cutting treatment of Example 1, and this is kneaded in the same manner as in the kneading and amalgamation treatment of Example 1 to cut the skin material of the waste material. Pellets were obtained in which the fiber resin of the material was dispersed in the form of a phase-separated body of 20 μm or less in an amalgam of the polypropylene of the base sheet in the waste and the added unused polypropylene. The pellets are formed into a sheet in the same manner as in Example 1, but in this case, a blowing agent is added in the same manner as above and the pellets are fed into an extruder.
A sheet-like foam (thickness: 2.4 mm) was obtained. This sheet is laminated to the skin material and reused.

Comparative Example 1 The same waste material as in Example 1 was used, and the cutting treatment, kneading and fusion treatment, and sheeting treatment in Example 1 were carried out in the same manner as in Example 1, except for the following points. A base sheet was manufactured. That is, the processing temperature in the kneading extruder in the kneading and fusion treatment was set to a maximum of 210°C. In the pellets obtained by the kneading extruder, the fiber resin of the waste skin material was dispersed in a phase-separated body with a size of 20 μm or more in the fusion of the polypropylene of the waste base sheet and the added unused polypropylene. .

Comparative Example 2 The same waste material as in Example 2 was subjected to the cutting treatment, kneading and fusion treatment, and sheeting treatment in Example 2 in the same manner as in Example 2, except for the following points, and a base material in the form of a foam was obtained. The sheet was manufactured. That is, the processing temperature in the kneading extruder in the kneading and fusion treatment was set to a maximum of 210°C. As a result, the pellets obtained by the kneading and fusion treatment are such that the fiber resin of the skin material of the waste is dispersed in the polypropylene of the base sheet of the waste and the added unused polypropylene fusion material in a phase separator of 20 μm or more. Was.

Comparative Example 3 The same waste material as in Example 1 was used, the skin material of this waste material was not separated, and in the cutting process, it was not cut into small dice as in Example 1, but randomly cut. (pieces with a length of 1 to 50 mm are mixed in an unspecified ratio), omitted the kneading and amalgamation process, and immediately formed into a sheet using a single-screw extruder in the same manner as in Example 1, A recycled solid sheet was obtained.

Comparative Example 4 Using the same waste material as in Example 2, the cutting treatment was carried out in accordance with Example 2 without separating the skin material from this waste material.
As shown in Example 2, the pieces were not cut into small dice but were randomly cut (pieces with a length of 1 to 50 mm were mixed in an unspecified proportion), the kneading and fusing process was omitted, and the mixture was immediately prepared in Example 2. Forming into a sheet was carried out in the same manner as in , to obtain a recycled sheet-like foam.

Comparative Example 5 The same waste as in Example 1 was used, but in this example, the skin material was separated and only the base sheet was treated. In the waste cutting process, the waste was randomly cut into irregularly shaped products similar to those in Comparative Example 3, the kneading and fusion process was omitted, and the waste was immediately subjected to the sheeting process in the same manner as in Example 1 to obtain recycled solid sheets. Ta.

Comparative Example 6 The same waste as in Example 2 was used, but in this example, the skin material was separated and only the base sheet portion was treated. In the waste cutting process, the waste was randomly cut into irregular-shaped products similar to those in Comparative Example 4, the kneading and fusing process was omitted, and the waste was immediately subjected to the sheeting process in the same manner as in Example 2 to produce recycled sheet-like foam. I got it.

[0033] Regarding Examples 1 and 2 and Comparative Examples 1 to 6, the quality of handling of the raw material resin during processing and the quality of stable productivity when forming sheets using recovered products were evaluated, and the quality of sheet production was evaluated. The strength of the recycled sheet obtained by the chemical treatment was measured. The results are shown in Table 1. Note that these evaluation criteria and measurement methods are as follows.

Resin handling: In Examples 1 and 2 and Comparative Examples 1 and 2, during the kneading and fusion treatment, when feeding the cut pieces to the extruder, and in Comparative Examples 3 to 6, When supplying cut pieces to the extruder during the sheeting process, it is best if the pieces flow smoothly in the extruder hopper, and bridging occurs in the hopper, causing the flow of the pieces. A case where a problem occurs is considered defective. Stable production of sheets: During sheet processing, it is considered good if sheets can be produced stably for more than one hour, and within one hour,
If the thickness of the sheet varies (due to the fibers of the skin material remaining in the raw material pellets), it is considered defective. Strength of recycled sheet: Impact strength (kg·cm) value measured in accordance with ASTM D 2794.

[0035]

[Table 1]

Looking at Table 1 above, in Comparative Examples 1 and 2, the handling of the resin and the stable productivity of the sheet are both good because the trimming loss is cut into small pieces. When this happens, the strength of the resulting sheet is low. In Comparative Examples 3 and 4, the trimming loss was not cut into small pieces, so the handling properties of the resin, stable sheet productivity, and strength of the recycled sheet were all poor. In Comparative Examples 5 and 6, when trimming loss is recycled, the skin material is separated, so the handling of the resin, the stable productivity of the sheet, and the strength of the recycled sheet are all good, but the skin material of the trimming loss is good. It cannot be reused and requires the complicated work of separating only the skin material from trimming losses of various shapes and sizes. Examples 1 and 2 of the present invention do not have any of the above problems.

[0037]

[Effects of the invention] Waste such as trimming loss generated when thermoforming a sheet-like laminate formed by laminating a base sheet and a skin material can be recycled without separating the skin material, and the waste can be recycled. To avoid operational troubles due to the presence of the skin material during processing, and to not adversely affect the strength of the resulting sheet when it is recovered and recycled into sheets.

Claims (1)

[Claims] Claim 1: A solid base sheet made of a polyolefin thermoplastic resin containing 50% by weight or more of a propylene component and/or an ethylene component, a foam base sheet made of the above polyolefin thermoplastic resin, or the above solid. A sheet-like laminate is thermoformed by laminating a woven or nonwoven fabric made of thermoplastic resin fibers as a skin material on a base sheet formed by laminating a base sheet in the form of a foam and a base sheet in the form of a foam. A method for recycling waste generated in a process, the waste being cut into small pieces without substantially removing the fibers of the skin material from the waste,
These strips are fed into a kneading extruder with or without addition of the raw material resin of the base sheet and kneaded at a temperature higher than the melting point of the resin of the base sheet and the fiber resin of the skin material, The resin of the fibers and the resin of the base sheet are mutually soluble, or the resin of the fibers is 20 μm thick in the resin of the base sheet.
The pellets are kneaded until they are dispersed in the form of phase-separated bodies of the following sizes, collected as pellets, and the pellets are formed by laminating the above-mentioned solid-form base sheet, foam-form base sheet, or both of these sheets. A method for recycling waste during processing of a laminate, characterized in that it is used for manufacturing a base sheet.